The proposed study is designed to determine the effects of including mastery criteria for teaching eating and exercise behavior change as part of a family-based treatment program for childhood obesity. Behavioral programs for childhood obesity specify the target behavior to be changed and arrange reinforcement contingencies for these changes. However, there is still considerable variability in the extent to which children learn these new eating and exercise behaviors, and consequently considerable variability in the weight losses achieved. This study assesses the effects of introducing mastery criteria, in which a child and parent will progress through the program at the rate he/she has mastered the material, and demonstrated the desired behavior change. This Paced/Mastery program will be compared to a fixed-pace/Non-mastery Control group, which constitutes the conventional treatment protocol, and a Paced/Yoked Control group, in which progress through the program is dependent on the progress of a child or parent in the Paced/Mastery group. It is predicted that children and their parents that are provided with mastery criteria will show better learning and retention of the written material and the behavioral skills than subjects in the two control groups. In addition, weight losses in the three groups should be different, with the weight changes showing the same pattern of results as the behavioral skills.